platform_bionic/libc/arch-x86/generic/string/strncmp.S
Haibo Huang b9244ff551 Use ifunc to dynamically dispatch libc routines for x86
Test: run bionic unit test in aosp_cf_x86_phone emulator
Change-Id: Ib0c0de37cd38d24bfce2dfbe35b8fd8edff004af
2018-11-13 13:48:23 -08:00

114 lines
1.5 KiB
ArmAsm

/* $OpenBSD: strncmp.S,v 1.3 2005/08/07 11:30:38 espie Exp $ */
/*
* Written by J.T. Conklin <jtc@netbsd.org>.
* Public domain.
*/
#include <private/bionic_asm.h>
/*
* NOTE: I've unrolled the loop eight times: large enough to make a
* significant difference, and small enough not to totally trash the
* cache.
*/
ENTRY(strncmp_generic)
pushl %ebx
movl 8(%esp),%eax
movl 12(%esp),%ecx
movl 16(%esp),%edx
testl %edx,%edx
jmp L2 /* Jump into the loop! */
.align 2,0x90
L1: incl %eax
incl %ecx
decl %edx
L2: jz L4 /* strings are equal */
movb (%eax),%bl
testb %bl,%bl
jz L3
cmpb %bl,(%ecx)
jne L3
incl %eax
incl %ecx
decl %edx
jz L4
movb (%eax),%bl
testb %bl,%bl
jz L3
cmpb %bl,(%ecx)
jne L3
incl %eax
incl %ecx
decl %edx
jz L4
movb (%eax),%bl
testb %bl,%bl
jz L3
cmpb %bl,(%ecx)
jne L3
incl %eax
incl %ecx
decl %edx
jz L4
movb (%eax),%bl
testb %bl,%bl
jz L3
cmpb %bl,(%ecx)
jne L3
incl %eax
incl %ecx
decl %edx
jz L4
movb (%eax),%bl
testb %bl,%bl
jz L3
cmpb %bl,(%ecx)
jne L3
incl %eax
incl %ecx
decl %edx
jz L4
movb (%eax),%bl
testb %bl,%bl
jz L3
cmpb %bl,(%ecx)
jne L3
incl %eax
incl %ecx
decl %edx
jz L4
movb (%eax),%bl
testb %bl,%bl
jz L3
cmpb %bl,(%ecx)
jne L3
incl %eax
incl %ecx
decl %edx
jz L4
movb (%eax),%bl
testb %bl,%bl
jz L3
cmpb %bl,(%ecx)
je L1
.align 2,0x90
L3: movzbl (%eax),%eax /* unsigned comparision */
movzbl (%ecx),%ecx
subl %ecx,%eax
popl %ebx
ret
.align 2,0x90
L4: xorl %eax,%eax
popl %ebx
ret
END(strncmp_generic)